SLB or Simple Load Balancer is a tool designed to simplify the task of load balancing between a set of servers. It monitors a set of servers and uses SNMP protocol to periodically collect a set of parameters from each of them. Once obtained, these parameters are used as arguments to a load estimation function, which computes, for each server, a floating point value representing its relative load. SLB then sorts the servers in the order of increasing relative load.

SLB does not attempt to actually correct the load distribution, as this task depends heavily on the kind of work the servers are performing and it is difficult, if not impossible, to provide a generalized solution for that. Instead, SLB relies on an external program which is supposed to redistribute the load, based on the data obtained from it. Therefore, after obtaining the sorted list of servers, SLB filters it through a user-defined format template, and sends the result to a file, named pipe or another program.

All parameters used by SLB, including load estimation function, are supplied to it in a user-defined configuration file, which makes the package extremely flexible.